The brains of a mouse type that develops Alzheimer's at a young age keep functioning well for longer if the animals are given extracts of milk thistle [Silybum marianum] mixed with their food, researchers at the Tokyo Metropolitan Institute of Gerontology discovered.
Supplementation with Silybum marianum – the plant is also known as milk thistle – induces liver cells to synthesise more glutathione, a detoxifier which improves the functioning of the liver. Animal studies have shown that Silybum marianum protects the liver against the effects of oral anabolic steroids. [Med Pregl. 2003;56 Suppl 1:79-83.]
It is also possible that the plant has a similar protective effect on the prostate. [Integr Cancer Ther. 2007 Jun; 6(2): 130-45.] Prostate cancer may occur as a result of the decrease in production of detoxifying enzymes that occurs with aging. [Exp Gerontol. 2012 Mar; 47(3): 223-8.] There are also indications that Silybum marianum blocks the growth-enhancing effects of androgens on prostate cancer cells. [Carcinogenesis. 2001 Sep;22(9):1399-403.]
The Japanese researchers wanted to know whether milk thistle had similar positive effects in the brain. Silybum marianum reduces the accumulation of fats and cholesterol in the body, was their reasoning. And this accumulation resembles, to some extent, the accumulation of beta-amyloid plaques in the brains of Alzheimer's sufferers. These plaques interfere with the brain's functioning. So, might Silybum marianum inhibit the formation of these plaques?
To answer this question the Japanese did an experiment with mice that had been genetically modified so that they synthesised plaques [Tg]. Alzheimer's researchers often use this kind of mice for their studies. The researchers gave half of their lab animals food consisting of 0.1 percent Silybum marianum for six months. At the end of this period they subjected the mice to psychological tests and studied their brains.
In one trial the researchers put the mice in a cage with three runs. The Japanese then recorded how often the mice entered the runs. Animals with Alzheimer's are less calm than healthy animals. In this kind of situation they keep on checking out their surroundings – probably because their brains do not retain a memory of earlier forays around the cage.
The figure below shows that months of supplementation with Silybum marianum had no effect on the behaviour of normal mice [Wt], but did reduce the number of times that the Alzheimer's mice checked out their surroundings.
The photos above show samples of brain tissue. The upper row shows tissue from mice at the start of supplementation. The bottom row shows brain tissue from Alzheimer's mice aged one year. The dots are plaques.
The figures below are self-evident. Supplementation with Silybum marianum reduced the formation of the blocks of which beta-amyloid plaques are composed, and inhibited the process through which the building blocks form plaques.
The Japanese converted the Silybum marianum dose they used to a dose for humans, and arrived at 16 mg/kg/day. That is twice the amount of the dose that researchers in Iran tried out in a 4-month trial on people with diabetes type-2, where they encountered no problems. [Phytother Res. 2006 Dec;20(12):1036-9.]
Biosci Biotechnol Biochem. 2010;74(11):2299-306.